Question

The Java hotspot vpm can be run with -client or -server argument. If neither is specified then it chooses one according to some rules.

Is it possible to tell whether a running VM is running in client or server mode when the mode is not specified on command line? I need this on a Windows box outside the running process.

I realize this is not a programming question, but I hope it is ok because it is programming related. Thanks in advance.

Answer 1

In Java, you could check this with this code:

String s = System.getProperty("java.vm.name");
// s = Java HotSpot(TM) Server VM

But this will be highly vendor specific.

From the command line, you could use jinfo (used to check a value of a given HotSpot VM option)

C:\>"c:\Program Files\Java\jdk1.6.0_16\bin\jps.exe" -l -m
21812 sun.tools.jps.Jps -l -m
19244 (eclipse)

C:\>"c:\Program Files\Java\jdk1.6.0_16\bin\jinfo.exe" -flag NewRatio 19244
-XX:NewRatio=12

Since:

• it is rare to actually set the NewRatio Hotpot option and
• the documentation specifies: Ratio of new/old generation sizes. [x86 -server: 8; x86 -client: 12]

12 means “Client”.